Tape severing device

ABSTRACT

An improvement in a device for severing strip material. The device includes a first wheel supporting a fixed cutting member, and a second wheel supporting a pivotal spring biased cutting member. The wheels are spaced and synchronously driven to bring edges on the cutting members into periodic shearing engagement with strip material fed therebetween during an intersecting path portion for the cutting members. The improvement comprises a cam actuated arm for moving the pivotal cutting member out of engagement with the fixed cutting member subsequent to engagement of their cutting edges and prior to the end of their intersecting path portions.

United States Patent n91 Toensing 1 Aug. 7, 1973 1 TAPE SEVERING DEVICE [73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

[22] Filed: Aug. 2, 1971 [21] Appl. No.2 167,924 I [52] US. Cl 83/337, 83/342, 83/348 [51] Int. Cl 823d 25/12 [58] Field of Search 83/337, 348, 342

[56] References Cited UNITED STATES PATENTS 3,084,582 4/1963 Anderson 83/348 X 3,138,074 6/1964 Hartbauer 83/348 X 1,853,434 4/1932 Kling 83/337 2,738,842 3/1956 Huck 83/341 1,139,528 5/1915 Huffman 83/337 Primary Examiner-.1. M. Meister Altorney-Alexander, Sell, Steidt & Delahunt [57] ABSTRACT An improvement in a device for severing strip material. The device includes a first wheel supporting a fixed cutting member, and a second wheel supporting a pivotal spring biased cutting member. The wheels are spaced and synchronously driven to bring edges on the cutting members into periodic shearing engagement with strip material fed therebetween during an intersecting path portion for the cutting members. The improvement comprises a cam actuated arm for moving the pivotal cutting member out of engagement with the fixed cutting member subsequent to engagement of their cutting edges and prior to the end of their intersecting path portions. I

2 Claims, 7 Drawing Figures Patented Aug. 7, 1973 1 sheets-sheet 1 INVENTOR. g M55 W TOENS/NG M fla /AW? ATTORNEYS Patented Aug. 7, 1973 4 Sheets-Sheet 3 m m o s N Wm m T WTO MM; L A W m.

Patented Aug. 7, 1973 3,750,511

4 Sheets-Sheet (5 94 JAMES W TOENS/NG 75 Y ,flz xd rw m F106 MW QQZOQW ATTORNEYS INVENTOR.

Patented Aug. 7, 1973 1 Sheets-Shoe t 4 6 5 KW U ws N AN R 55 0 W JA 1 "Cu. WWW J M TAPE SEVERING DEVICE FIELD OF THE INVENTION This invention relates to devices for severing tape and in one aspect to a device particularly adapted for severing predetermined lengths of tape on a machine for applying the lengths of tape to a continuously moving surface.

BACKGROUND OF THE INVENTION Devices are known for severing predetermined lengths of tape on machines for applying the lengths of tape to a surface or series of articles in continuous motion. Such a machine illustrating several types of severing devices is disclosed in US. Pat. No. 2,990,081 This machine comprises a rotatably mounted tape applying wheel and vacuum means operative within the wheel to hold the severed length of tape against the peripheral surface of the wheel adhesive side out. The tape is transferred to an article when the article and the wheel bear against each other at a tape applying station with the tape between them. The illustrated devices for severing. the predetermined lengths of tape generally include means for pressing the cutting edge of a knife against a planar anvil surface on the periphery of the tape applying wheel to sever a predetermined length from a tape fed between the knife and the applying wheel. One embodiment which affords the advantage of continuous rotational movement of both the anvil and the knife comprises a series of knives cantilevered from a second wheel and rotated in synchronism with the tape applying wheel to afford sequential engagement of cutting edges on the knives with mating anvil surfaces on the periphery of the applying wheel to crush the tape therebetween. While this severing means has proved suitable for severing adhesive coated material at over 800 cuts per minute, this device may present certain undesirable adjustment and maintenance problems. A high degree of force must be exerted by each cutting edge against the anvil to sever the tape. This force is provided by precise spacing of each knife with respect to its mating'anvil to cause a few thousandths of aninch deflection of the knife, thereby providing a force for crush cutting of the tape. The machine must be ruggedly and very precisely made to'afford accurate positioning of the knives and anvils despite the forces exerted and requires periodic adjustment to compensate for wear of the cutting edges.

SUMMARY OFTHE INVENTION A device according to the present invention severs strip material or tape in a known manner by shearing action provided by interaction of a first cutting member disposed on a first wheel which may be a vacuum wheel and a second cutting member rotated by a second wheel into shearing engagement therewith. One of the cutting members is pivotally mounted on the wheel and is spring biased for engagement with the mating cutting member during their intersecting path portions so that the device affords a degree of self alignment to provide the proper cutting relationship between the cutting edges without abnormal machining tolerances or excessive adjustment due to wear of the cutting edges. Flexure is not required in the cutting members thereby allowing them to be made of more brittle materials which afford greater edge retention (e.g. Tungsten Carbide) than do flexible cutting members.

The improvement of the present invention provides separation of the cutting members subsequent to shearing engagement of the cutting edges and while their paths are intersecting. This prevents sudden movement of the pivotal cutting member against its stops under the influence of the biasing means which could otherwise happen as the cutting members are separated subsequent to their intersecting path portions. This separation restricts damage to the cutting member and wheel during high speed operation. The separation in the present invention is afforded by an arm pivotally mounted on the wheel for engagement with the pivotal cutting member and cam means between the arm and the frame of the device to move the arm and separate the cutting members subsequent to engagement of their cutting edges.

BRIEF DESCRIPTION OF THE DRAWING The invention will be further described with reference to the accompanying drawing wherein like numbers refer to like parts in the several views, and wherein:

FIG. 1 is a front elevational view of a tape applying machine constructed according to the present invention;

FIG. 2 is a rear elevational view of the machine of FIG. 1 illustrating the drive mechanism;

FIGS. 3, '4 and 5 are enlarged fragmentary detail views of the cutting device showing sequentially the operation of the cutting bar and the blade to sever a length of strip material;

' FIGJ6 is a fragmentary sectional-view taken approximately along line 66 of FIG. 3; and

FIG." 7 is a fragmentary sectional view of the blade taken approximately along line. 7-7 of FIG. 6.

DESCRIPTION OF THE INVENTION FIG. 1 shows a machine 10 for applying predetermined lengths of a strip material or tape 12 in spaced intervals to a continuously moving surface which may be comprised of a series of articles, or as illustrated, be a continuous web 14. The machine 10 includes a device for severing the tape 12. The device includes a pair of cutting members or cutting bars 16 having "cutting edges 20 mounted for rotation on a vacuum applying wheel 18. The wheel 18 is rotatably driven in the direction indicated by an arrow to bring the cutting edges 20 into timed sequential shearing engagement with cutting edges 22 on a pair of cutting members or blades 24 mounted for rotation on a cutting wheel 26, and driven as indicated in a rotational direction opposite that of the applying wheel 18 to move the blades along an intersecting path with the cutting bars 16 between the wheels 18 and 26.

The tape 12 to be severed is fed from a freely rotatable supply roll 28 around a driven roller 30 contacted by the adhesive side of the tape 12. The roller 30 is driven to advance the tape 12 at a continuous predetermined rate from the supply to feed the predetermined length of tape 12 to be severed during the rotational interval-of the wheels 18 and 26 between engagement of the cutting members. The tape 12 is then led around rollers 34 and 36 on an advancing mechanism 38 to be explained later for affording movement of the advancing length of tape 12 in synchronism with the cutting edges 20 and 22 during engagement thereof, and onto the peripheral surface of the applying wheel 18.

The machine is equipped with vacuum means for drawing the tape 12 against the surface of the wheel 18. A vacuum source (not shown) connected through the gauge 40 to a manifold 42 and a rotary union (not shown) creates a vacuum in a chamber formed within the applying wheel 18. The chamber communicates with the tape 12 through openings in the rim of the wheel 18. The distal end of the tape 12 is urged along the path of the periphery of the applying wheel 18; however, the wheel 18 is driven at a peripheral speed exceeding the advancing speed of the tape so that relative motion will occur between the distal end of the tape 12 and periphery of the wheel 18 except when these speeds are matched by the advancing means during severing of the tape 12.

Upon severing of a predetermined length of tape by interaction of the cutting edges 20 and 22, the severed length of tape 12 is retained against the periphery of the wheel 18 adhesive side out by the vacuum means and is moved therewith about the path into engagement with the surface of the web 14 at a tape applying station 43.

Advancing means are provided for advancing the tape 12 in synchronism with the cutting edges 20 and 22 and at the same linear speed during engagement thereof. The advancing means includes the roller 30 which is driven at a predetermined peripheral speed for advancing the predetermined length of tape 12 along the tape path between engagements of a blade 24 and cutting bar 20. The advancing means also includes an advancing mechanism 38 for increasing the velocity of the distal end of the tape 12 above the velocity imparted by the tape drive roller 30 to match the velocity of the tape with that of the cutting edges 20 and 22 during their engagement. This matched velocity prevents the blade 24 from being pulled out of engagement with the cutting bar 20 by the tape 12 and affords a square severed edge on the tape 12. Additionally the advancing means affords excellent positioning of the severed lengths of tape on the surface 14, as the movement of the length of tape to be severed before and after severing remains in synchronism with the periphery of the wheel 18.

The advancing mechanism 38 comprises the tape guide roller 34 and the guide roller 36 which are both rotatably mounted on a plate 44. The plate 44 is pivotally mounted on a pin 46 on a frame 29 of the machine 10 and is reciprocated via an adjustable length connecting rod 48 pivotally connected between a pin 50 on the plate 44 and a pin 52 eccentrically located on a crank wheel 54. The crank wheel 54 is driven in a clockwise direction as shown in FIG. 1 and is timed to be in the illustrated position during engagement of a pair of the cutting edges 20 and 22. In the illustrated position the rod 48 imparts a counter-clockwise rotation to the plate 44 and, together with the feed roller 30, afi'ords movement of the distal end of the tape 12 in synchronism with the periphery of the applying wheel 18 under the influence of the vacuum means. Subsequent to engagement of the cutting edges 20 and 22 further rotation of the wheel 54 slows and reverses rotation of the plate 44, thus separating the distal end of the tape 12 from the cutting edge 20.

The drive means for driving the various members of the device is shown in FIG. 2, which is a rear elevational view of the frame 29 upon which the device is mounted. The drive means comprises a motor 56 which may be a DC. variable-speed motor with a suitable control circuit (not shown). The motor 56, through a sprocket and chain assembly 58, drives the shaft supporting the cutting wheel 26 in the direction indicated. A sprocket 60, also attached to the shaft of the wheel 26, through a chain 62 drives a sprocket 64 attached to the shaft of the tape feed roller 30, a sprocket 66 attached to the shaft of the crank wheel 54, a sprocket 68 attached to the shaft of the vacuum wheel 18, an idler sprocket 70, and a sprocket 72 attached to the shaft of an oiler wheel 73. The sprockets 60 and 68 as illustrated are of the same diameter and are rotatably positioned and driven in the contra-rotational direction indicated to afford engagement of a pair of the cutting edges 20 and 22 during each 180 rotation of the sprockets. The sprocket 66 driving the eccentric wheel 54 is sized to have a number of teeth which are evenly divisible into the number of teeth on the sprocket 68 driving the vacuum wheel 18, with such division resulting in a number which is equal to or a multiple of the number of cutting bars 16 on the wheel 18 so that the advancing mechanism 38 may be timed to produce similar advancement of the tape 12 during each engagement of a pair of cutting edges 20 and 22.

Referring now to FIGS. 1 and 3 through 7, the cutting members comprising the device for severing the tape 12 will be more fully described. The cutting bars 16 formed with the cutting edges 20 are mounted in recesses disposed at 180 spacing about the periphery of the vacuum wheel 18. The cutting bars 16 are disposed with the cutting edges 20 at the periphery of the wheel 18 and parallel to the axis of rotation. Each cutting bar 16 is formed with a blade portion 78 having a width generally equal to that of the wheel 18 and a central portion 80 through which the bar 16 is attached to the wheel 18 as by screws.

The blades 24 (best seen in FIGS. 3 through 7) are plate-like members having a width generally equal to the blade portion 78 of the cutting bars 16. Each blade 24 has a planar contact surface 84 with the cutting edge 22 (illustrated as V-shaped to produce opposed equal shearing forces transverse to the tape) formed adjacent one end along the contact surface 84. Each blade 24 is formed with two parallel guide members 86 extending beyond the cutting edge 22 and having radiused end portions along the contact surface 84. The width of the cutting edge 22 between the guide members 86 is slightly greater than the width vof the central portion 80 of the cutting bars 16 and generally defines the maximum width of out which may be made on the tape 12. Means are provided for engaging a blade 24 and a cutting bar 16 during theintersecting portion of the path to bring the contact surface 84 on the guide members 86 into contact with the cutting edge 20 on the cutter bar 16 and to bias the contact surface 84 against the cutting edge 20 while the cutting edges 20 and 22 are moved into shearing engagement. Means are also provided for separating the blade 24 and cutter bar 16 during the intersecting path portion after engagement of the cutting edges 20 and 22 to sever the tape 12.

The wheel 18 is spaced from the wheel 26 to provide the intersecting path portions for the cutting edges 20 on the cutter bar 16 with the cutting edges 22 and with the guide members 86 on the knives 24 as may most clearly be seen in FIGS. 3, 4 and 5. The radius of the guide members 86 and cutting edges 22 of the knives 24 on the wheel 26 exceeds the radius of the cutting edges of the cutter bars 16 on the wheel 18 so that as the wheel 18 and the wheel 26 are driven at equal rotational speeds the guide members 86 and cutting edges 22 have a slightly higher peripheral speed than the peripheral speed of the cutting edges 20 on the cutting bars 16.

Each blade 24 is pivotally mounted on the wheel 26 via a semi-spherically tipped pivot bolt 88 which engages a corresponding socket formed in the contact surface of the blade 24. Each blade 24 is held in position on the pivot bolt 88 by a biasing means or spring 90 positioned between the knife 24 and the head of an adjustable bolt 92. The bolt 92 passes through a clearance hole 93 in the knife 24 and engages the wheel 26. The spring 90 biases the knife 24 against the pivot bolt 88 and a pair of locating bolts 94 adjustabiy mounted in a leg of a crank arm 96 pivotally mounted on the wheel 26 about a pin 98. The crank arm 96 provides means for defining the position of the blade 24 on the wheel 26 and for varying the position of the guide members 86 of the blade 24 with respect to the periphery of the wheel 26 by pivoting the blade 24 about the bolt 88 on an axis generally parallel to the axis of the wheel 26. This position of the guide members 86 is controlled by cam 100 mounted on the frame and having an internal race 102 against which a follower wheel 104 rotatably mounted on the crank arm may be pressed by action of the spring 90. The major portion of the cam race 102 is circular and concentric with the wheel 26 to define a normal position of the blade 24 with respect to the wheel 26. The cam 100, however, is formed with a non-circular race portion 105 which allows rotation of the crank arm 96 and blade 24 from the normal position in the same rotational direction as the wheel 26 under the influence of the spring 90. The race portion 105 is located to allow the blade to rotate forward to contact the cutting bar 16 and to be pressed against the cutting edge 20 by the spring 90 during the first part of the intersecting path portion prior to engagement of the edges 20 and 22 to sever the tape 12, and rotates the blade 24 out of engagement with the cutting bar 16 during the intersecting path portion after engagement of the cutting edges 20 and 22 to avoid impacting the blade 24 againstthe bolts 94 as the tips of the guide members 86 leave the cutting bar 16.

Referring now to FIGS. 3,4 and 5, the interaction .of a pair of the cutting members will be sequentially dee scribed during the severing of a length of tape 12.

The wheels 18 and 26 are timed by the drive means, and the race portion 105 is positioned to move the contact surface 84 of the guide members 86 into engagement with the cutting edge 20 on the cutting bar 16 near the beginning of their intersecting path portions (FIG. 3). Subsequent to this contact the crank arm does not provide support for the blade 24 against the cutting edge 20. The blade 24 may also pivot slightly about the bolt 88 to compensate for misalignment between its contact surface 84 and the cutting edge 20 on the cutting bar 16.

Further rotation of the wheels 18 and 26 will slide the contact surface 84 on the guide members 86 across the cutting edge 20 and bring the cutting edges 20 and 22 into shearing engagement (FIG. 4) to sever the tape 12 which, due to the advancing means, is traveling at the same speed as the cutting edges and is positioned between the cutting edges 20 and 22. During engagement of the edges 20 and 22 the guide members 86 project into the recess in the applying wheel 18 on either end of the central portion of the cutting bar 16.

After the cutting edges have engaged (FIG. 5), the cam rotates crank arm 96 carrying the bolts 94 to pivot the blade 25 in a rotational direction opposite that of the wheel 26 and left the tips of the guide members 86 fromthe blade portion 78 to provide an impactfree separation of the blade 24 from the cutting bar 16.

It will be understood that various modifications of the severing device may be made without departing from the essence of the present invention. For example, the device may comprise more or less than two cutting bars and blades, and the number of cutting bars and blades may be dissimilar provided they are driven for proper engagement. The biasing of the blade against the cutting edge may be afforded only by differential speeds between the cutting edges, only by the cam means, or by the combination thereof disclosed in this specification. The cutting edge of the blade may be straight rather than V-shaped and inclinedxelative to the axis of the cutting wheel to afford, a severing in only one axial direction across the width of the tape. With this configuration only one guide member may be used if the blade is mounted for rotation about a fixed axis on the periphery of the cutting wheel 25 and the edge is inclined relative to the axis of the wheel in two planes. Additionally, either the blade or blade portion of the cutting bar may be slightly arcuate about an axis generally radial to the wheels 18 and 26 with the convex surface of the blade or concave surface of the blade portion toward the direction of rotation to insure contact between the cutting edges.

Having thus described the present invention, what is claimed is:

1. In a device for severing strip material, including:

a frame;

first and second axially parallel wheels rotatably mounted on said frame;

a first cutting member having a first cutting edge mounted on said first wheel with said first cutting edge at the periphery of said first wheel;

a second cutting member having ,a contact surface with a second cutting edge along one end and at least one guide member defining a portion of said contact surface extending beyond said second cutting edge at said one end, said second cutting member being mounted on said second wheel with said one-end radially extended; I

said wheels and cutting members being positioned to provide intersecting path portions for said cutting edges upon rotation of said wheels and to afford engagement of said contact surface against said first cutting edge when said cutting members are in said intersecting path portions;

one of said cutting members being mounted on the wheel for pivotal motion about an axis parallel to the axis of the wheel and said device including biasing means for biasing said pivotally mounted cutting member in a direction with its cutting edge beingthe leading edge; and I said device further includes means for synchronously driving said first and second wheels for contrarotation to engage the contact surface of said guide member with'the first cutting edge prior to the intersecting path portions of the edges and for main- 7 v 8 taining contact between said contact surface and pivoting said arm to contact said pivotally said first cutting edge under the influence of said mounted cutting member and move said contact biasing means during engagement of said cutting surface out of engagement with said first cutting edges, edge subsequent to engagement of said cutting the improvement wherein: edges when said cutting members are driven said device includes an arm pivotally mounted on through said intersecting path portion.

the wheel supporting said pivotally mounted cut- 2. A device according to claim 1, wherein said cam ting member, said arm having an end positioned means comprises: to contact and pivot said cutting member against a cam having a cam race fixedly mounted on said the bias of said spring upon pivoting of said end 10 frame; and toward said pivotally mounted cutting member; a follower on said arm adapted for movement along and said cam race. cam means between said arm and said frame for 

1. In a device for severing strip material, including: a frame; first and second axially parallel wheels rotatably mounted on said frame; a first cutting member having a first cutting edge mounted on said first wheel with said first cutting edge at the periphery of said first wheel; a second cutting member having a contact surface with a second cutting edge along one end and at least one guide member defining a portion of said contact surface extending beyond said second cutting edge at said one end, said second cutting member being mounted on said second wheel with said one end radially extended; said wheels and cutting members being positioned to provide intersecting path portions for said cutting edges upon rotation of said wheels and to afford engagement of said contact surface against said first cutting edge when said cutting members are in said intersecting path portions; one of said cutting members being mounted on the wheel for pivotal motion about an axis parallel to the axis of the wheel and said device including biasing means for biasing said pivotally mounted cutting member in a direction with its cutting edge being the leading edge; and said device further includes means for synchronously driving said first and second wheels for contrarotation to engage the contact surface of said guide member with the first cutting edge prior to the intersecting path portions of the edges and for maintaining contact between said contact surface and said first cutting edge under the influence of said biasing means during engagement of said cutting edges, the improvement wherein: said device includes an arm pivotally mounted on the wheel supporting said pivotally mounted cutting member, said arm having an end positioned to contact and pivot said cutting member against the bias of said spring upon pivoting of said end toward said pivotally mounted cutting member; and cam means between said arm and said frame for pivoting said arm to contact said pivotally mounted cutting member and move said contact surface out of engagement with said first cutting edge subsequent to engagement of said cutting edges when said cutting members are driven through said intersecting path portion.
 2. A device according to claim 1, wherein said cam means comprises: a cam having a cam race fixedly mounted on said frame; and a follower on said arm adapted for movement along said cam race. 